Cross-Reference to Related Applications

[0001] Priority is hereby claimed to U.S. Provisional Patent App. No. 61/140,598, filed December 23, 2008, the entire contents of which are herein incorporated by reference.

Background

[0002] Visco-elastic foam is sometimes used to form mattresses and other body supports, has the ability to conform to a user's body, and can provide pressure relief for the user's body. Many types of visco-elastic foam have a glass transition temperature at least partially within the range of temperatures at which a room can be or is likely to be maintained (e.g., 10-30 ⁰ C). Therefore, for such visco-elastic foams, the temperature of the visco-elastic foam at least partially determines the firmness of the body support. As the temperature of the body support's environment increases (such as by an increase in room temperature and/or by transmission of heat to the body support from a user's body), the firmness of the body support can be reduced. Alternatively, as the temperature of the body support's environment decreases (such as by a decrease in room temperature and/or reduction in the amount of heat provided to the body support by a user), the firmness of the body support can be increased.

[0003] A particularly desirable feature for many body supports is the ability to adjust the hardness of the body support. However, the ability to control the firmness of body supports comprising visco-elastic foam has heretofore been limited. Body supports comprising visco- elastic foam having a hardness that can be adjusted by a user would be welcome additions to the art.

Summary

[0004] In some embodiments, the present invention provides a body support comprising one or more layers of visco-elastic foam and one or more electric heating elements (e.g., resistive heating elements, Peltier devices, and the like) positioned to heat the visco-elastic foam. The body support can also include one or more sensors positioned to measure the temperature of the visco-elastic foam in one or more locations in or on the body support, and a controller coupled to the electric heating elements and sensor(s) to receive the temperatures detected by the sensor(s) and to change the output of the electric heating elements (e.g., by changing the current supplied to the electric heating elements) as a result. In this manner, the firmness of the body support can be adjusted in response to controlling the output of the electric heating elements, thereby changing the amount of thermal energy conducted to the visco-elastic foam.

[0005] In some embodiments, the present invention provides a body support having a first layer formed of a visco-elastic or non- visco-elastic foam, a second layer formed of a visco-elastic foam atop the first layer, one or more electric heating elements (e.g., resistive heating elements, Peltier devices, and the like) positioned to heat the visco-elastic foam of the first layer, and a thermally-conductive layer of material positioned to distribute heat from the electric heating elements to the second layer.

[0006] Some embodiments of the invention provide a body support assembly includes a layer including a visco-elastic foam, a heating element in thermal communication with the foam, a temperature sensor in thermal communication with the foam, and a controller coupled to the sensor and programmed to control the heating element based on input from the sensor.

[0007] Some embodiments of the invention provide a body support assembly including a layer comprising foam, a Peltier device in thermal communication with the foam, a temperature sensor in thermal communication with the foam, and a controller coupled to the sensor and programmed to control the Peltier device based on input from the sensor.

[0008] Other aspects of the present invention will become apparent by consideration of the detailed description and accompanying drawings.

Brief Description of the Drawings

[0009] Fig. 1 is a sectional view of a mattress according to an embodiment of the present invention.

[0010] Fig. 2 is an exploded view of the mattress in Fig. 1.

[0011] Fig. 3 is a schematic diagram of the mattress illustrated in Fig. 1, showing a controller in communication with a number of electric heating elements and a sensor of the mattress. Detailed Description

[0012] Before any embodiments of the present invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Also, terms such as "first", "second", and "third" are used herein and in the appended claims for purposes of description and are not intended to indicate or imply relative importance or significance unless otherwise specified. The term "first" does not necessarily refer to the top most layer, rather, it refers to the first of a plurality, without indicating a particular location or position. Similarly, the terms "top" and "bottom" are used for the purpose of description and are not intended to indicate or imply relative importance, significance, unless otherwise specified. The term "top" does not necessarily refer to the top most layer, and "bottom" does not necessarily refer to the bottom most layer.

[0013] The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms "mounted," "connected," "supported," and "coupled" and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, "connected" and "coupled" are not restricted to physical or mechanical connections or couplings.

[0014] Figs. 1-3 illustrate a body support 10 according to an embodiment of the present invention. In the illustrated embodiment, the body support 10 is a mattress. The illustrated body support 10 includes three layers of foam: a first layer 14, a second layer 18 positioned above the first layer, and a third layer 22 positioned above the second layer 18 such that the second layer 18 is positioned between the first layer 14 and the third layer 22. Some alternative embodiments of the body support 10 only have two layers of foam (e.g., the first and second layers 14, 18, or the first and third layers 14, 22) or even a single layer of foam, whereas in other embodiments, more than two layers of foam are used (e.g., one or more layers of foam between and/or atop the second and third layers 18, 22, between the first and second layers 14, 18, and/or beneath the first layer 14. The third layer 22 is shown removed from Fig. 3 for ease of illustration. [0015] In the illustrated embodiment, the first layer 14 comprises foam, such as a latex foam, reticulated or non-reticulated visco-elastic foam (sometimes referred to as "memory foam" or "low resilience foam"), or reticulated or non-reticulated non-visco-elastic foam, any polyurethane high-resilience (HR) foam, any expanded polymer (e.g., expanded ethylene vinyl acetate, polypropylene, polystyrene, or polyethylene), and the like, whereas the second and third layers 18, 22 comprise reticulated or non-reticulated visco-elastic foam.

[0016] Visco-elastic foam has unique low-resilience, slow-recovery, body-conforming, and pressure distributing properties that are inherently attractive for use in a wide variety of body support applications, including mattresses such as that shown in Figs. 1-3. The visco- elastic foam described herein (e.g., whether for use in the first layer 14, second layer 18, and/or third layer 22 of the illustrated embodiment) has a hardness of at least about 20 N and no greater than about 80 N for desirable softness and body-conforming qualities. In other embodiments, the visco-elastic foam has a hardness of at least about 30 N and no greater than about 70 N for this purpose. In still other embodiments, a viscoelastic foam hardness of at least about 40 N and no greater than about 60 N is utilized. Unless otherwise specified, the hardness of a material referred to herein is measured by exerting pressure from a plate against a sample of the material to a compression of 40% of an original thickness of the material at approximately room temperature (e.g., 21-23 Degrees Celsius), wherein the 40% compression is held for a set period of time, following the International Organization of Standardization (ISO) 2439 hardness measuring standard.

[0017] The visco-elastic foam described herein can also have a density providing a relatively high degree of material durability. The density of the visco-elastic foam can also impact other characteristics of the foam, such as the manner in which the visco-elastic foam responds to pressure, and the feel of the foam. In some embodiments, the visco-elastic foam has a density of no less than about 30 kg/m ³ and no greater than about 150 kg/m ³ . In other embodiments, a visco-elastic foam having a density of at least about 40 kg/m ³ and no greater than about 135 kg/m ³ is utilized. In still other embodiments, visco-elastic foam having a density of at least about 50 kg/m ³ and no greater than about 120 kg/m ³ is utilized.

[0018] The visco-elastic foam used in the various body support embodiments described and/or illustrated herein can be reticulated or non-reticulated visco-elastic foam. In this regard, reticulated visco-elastic foam has characteristics that are also well suited for use in the body support 10, including the enhanced ability to permit fluid movement through the reticulated visco-elastic foam, thereby providing enhanced air and/or heat movement within, through, and away from the reticulated visco-elastic foam. Reticulated foam (visco-elastic or otherwise) is a cellular foam structure in which the cells of the foam are essentially skeletal. In other words, the cells of the reticulated foam are each defined by a plurality of apertured windows surrounded by cell struts. The cell windows of reticulated foam can be entirely gone (leaving only the cell struts) or substantially gone. In some embodiments, the foam is considered "reticulated" if at least 50% of the windows of the cells are missing (i.e., windows having apertures therethrough, or windows that are completely missing and therefore leaving only the cell struts). Such structures can be created by destruction or other removal of cell window material, or preventing the complete formation of cell windows during the manufacturing process of the foam.

[0019] In some embodiments, the second layer 18 can be positioned between the first layer 14 and the third layer 22 without being secured thereto. However, in other embodiments, the first, second and third layers 14, 18, 22 are secured to one another by adhesive or cohesive bonding material, by being bonded together during formation of the first, second layers, and/or third layers 14, 18, 22, by tape, hook and loop fastener material, conventional fasteners, stitches extending at least partially though adjacent layers 14, 18, 22, or in any other suitable manner.

[0020] With reference to Figs. 1 and 2, each of the first, second, and third layers 14, 18, 22 can be substantially flat bodies having substantially planar top and bottom surfaces 26, 30, 34, 38, 39, 41. However, in other embodiments, one or more of the top and bottom surfaces 26, 30, 34, 38, 39, 41 of any of the first, second, and third layers 14, 18, 22 can be non-planar, including without limitation surfaces having ribs, bumps, and other protrusions of any shape and size, surfaces having grooves and other apertures that extend partially or fully through the respective layer 14, 18, 22, and the like. Also, depending at least in part upon the application of the body support 10 (i.e., the product defined by the body support 10 or in which the body support 10 is employed), any one or more of the first, second, and third layers 14, 18, 22 can have shapes that are not flat. By way of example only, any of these layers 14, 18, 22 can be generally wedge-shaped, can have a concave or convex cross-sectional shape, can have a combination of convex and concave shapes, can have a stepped, faceted, or other shape, can have a complex or irregular shape, and/or can have any other shape desired. [0021] One of the properties of visco-elastic foam is glass transition. The glass transition temperature of the visco-elastic foam can impact the degree of firmness or hardness of the body support 10 (i.e., the layers 14, 18, 22), such as by changing the firmness of the second and third layers 18, 22, and also by changing the firmness of the first layer 14 and other layers in those embodiments in which the first layer 14 and any other layers comprise visco- elastic foam. In some embodiments of the preferred embodiment, the glass transition temperature of the visco-elastic foam falls at least partially within the range of about 10 ⁰ C and about 30 ⁰ C. However, glass transition temperatures falling within a range of, for example, -5°C to 40 ⁰ C are possible. In the illustrated embodiment, the second and third layers 18, 22 change in firmness through a range of temperatures of the second and third layers 18, 22. The firmness of the body support 10 can thereby be adjusted by changing the temperature of the second and/or third layers 18, 22. In other words, the body support 10 has a variable firmness that is controlled by the temperature of the visco-elastic foam in the second and/or third layers 18, 22 (and in any other layer of the body support 10 comprising visco-elastic foam, in some embodiments).

[0022] As shown in Figs. 1 and 2, the body support 10 includes a thermoelectric system 42 for heating and/or cooling the visco-elastic foam within the body support 10, and a thermally-conductive layer of material 46 positioned between the first and second layers 14, 18 of the body support 10. In the illustrated embodiment, the thermoelectric system 42 includes a number of Peltier devices 50, whereas in other embodiments, the thermoelectric system 42 can also or instead include resistive heaters which convert electric energy to heating energy, and/or other thermoelectric devices. Each Peltier device 50 is able to heat and cool the first and second layers 14, 18 (as well as additional layers of the body support, if present). In other embodiments, any or all of the Peltier devices 50 can be used exclusively to heat the first and second layers 14, 18. In such embodiments, other Peltier devices 50 can be used exclusively to cool the first and second layers 14, 18. Hereinafter, reference is only made to Peltier devices 50 for ease of description, it being understood that the following description of the possible locations, arrangements, and operation of Peltier devices 50 applies equally to resistive heaters and any other type of thermoelectric element desired.

[0023] By heating and/or cooling viscoelastic foam of the second and third layers 18, 22 (and the first layer 14, in those embodiments in which the first layer 14 comprises viscoelastic foam), the Peltier devices 50 are able to adjust the firmness in the body support 10 or a particular area of the body support 10 (e.g., an end of the body support 10, a side of the body support 10, an interior region of the body support 10, and the like).

[0024] The Peltier devices 50 of the illustrated embodiment are positioned along and recessed into the top surface 26 of the first layer 14 so as to be substantially flush with the top surface 26. However, in other embodiments, some or all of the Peltier devices 50 are located atop of and extend beyond the top surface 26 of the first layer 14, or are located below the top surface 26 of the first layer 14. In still other embodiments, Peltier devices 50 are recessed within the bottom surface 38 of the second layer 18, located inside the second layer 18, located between the second and third layers 18, 22 (whether recessed within the surfaces thereof 34, 39 or otherwise), or are located inside the third layer 22.

[0025] In the illustrated embodiment, the Peltier devices 50 are arranged into a single group and are substantially centrally positioned along the top surface 26 of the first layer 14 of the body support 10. The thermoelectric system 42 (e.g., the illustrated Peltier devices 50) is able to adjust the temperature of the second and third layers 18, 22 of the body support 10 and thereby adjust the firmness of the visco-elastic foam of the second and third layers 18, 22 that surround the thermoelectric system 42. In other words, the portions of the visco-elastic foam in thermal communication with the Peltier devices 50 receive heat from or transmit heat to the Peltier devices 50, thereby changing the firmness of the body support 10. Generally, the thermoelectric system 42 has the strongest effect in changing the firmness of the body support 10 in the immediate region surrounding the Peltier devices 50 of the thermoelectric system 42.

[0026] In some embodiments, the thermoelectric system 42 includes Peltier devices 50 arranged into two or more groups each positioned in different, separate locations along the length "L" and width "W" of the body support 10 (e.g., within or atop the first layer 14, as shown in the illustrated embodiment, or in any other location in the depth of the body support 10 as described herein). In this way, the thermoelectric system 42 can independently adjust the temperature (and therein the firmness) of the body support in two or more separate areas of the body support 10. For example, a first group of one or more Peltier devices 50 can be positioned in a first region 54 of the body support 10 (e.g., corresponding to the legs of a user resting upon the body support 10), whereas a second group of one or more Peltier devices 50 can be positioned in a second region 58 of the body support (e.g., corresponding to the torso of a user resting upon the body support 10), thereby enabling the firmness of the leg region to be changed independently of the torso region. In the first and second regions 54, 58, the Peltier devices 50 can heat and/or cool the layers 18, 22 to decrease or increase, respectively, the firmness sensed by the user at such regions. As another example, the regions just referred to can correspond to different sides of a body support 10 dimensioned to support two reclining users in side -by- side relation, thereby enabling the firmness of one user's portion of the body support 10 to be changed independently of the other user's portion. Again, the Peltier devices 50 in such regions can heat and/or cool the layers 18, 22 to decrease or increase, respectively, the firmness sensed by the users at such regions. Any number and combination of regions along the length and width of the body support 10 are possible for any degree of control over the body support 10 and regions thereof.

[0027] As mentioned above, the body support 10 of the illustrated embodiment includes a layer 46 of thermally-conductive material. This layer 46 can be used to more effectively conduct and distribute heat within the body support 10 (e.g., to and from the Peltier devices 50). In particular, the layer 46 of thermally-conductive material can be a layer of metal foil or other thermally-conductive material that transmits thermal energy from the Peltier devices 50 to the surfaces 26, 38 of the first and second layers 14, 18 positioned adjacent the heat conducting layer 46. The layer 46 can have any length and width relative to the length "L" and width "W" of the body support 10, and in the illustrated embodiment extends substantially the entire length "L" and width "W" of the body support 10. Other embodiments of the body support 10 do not utilize the layer 46 of thermally-conductive material.

[0028] In some embodiments, one surface of the layer 46 of thermally-conductive material can be provided with a thermally insulating material positioned, for example, adjacent the second layer 18, with the opposite thermally-conductive side of the layer 46 positioned adjacent the thermoelectric system 42 and the first layer 14. In operation, as the thermoelectric system 42 supplies thermal energy to the body support 10, the insulating surface of the layer 46 resists the transmission of thermal energy to the second layer 18, whereas the opposite thermally conducting surface of the layer 46 allows transmission of thermal energy to the first layer 14 via the top surface 26. In those embodiments in which the first layer 14 comprises visco-elastic foam, the first layer 14 provides firmness-adjusting capabilities while the second and third layers 18, 22 remain in a substantially steady- state (non-changing firmness) as the temperature of the first layer 14 changes. In other embodiments, the layer 46 just described can be flipped in order to insulate the first layer 14 against heat transmission, while transmitting and distributing thermal energy to and from the second and third layers 18, 22 to change the firmness of the second and third layers 18, 22.

[0029] Electric energy can be supplied to the thermoelectric system 42 by, for example, a portable power source, such as a battery (not shown), or by any other electric power source (e.g., household or building electric power circuit). The battery can be embedded into any portion of the body support 10, in some embodiments.

[0030] As shown in Figs. 2 and 3, the body support 10 of the illustrated embodiment also includes a sensor 62 and a controller 66 in communication with the sensor 62. The controller 66 can be powered by the same power source as the thermoelectric system 42 or any other power source. The controller 66 in the illustrated embodiment is also coupled to the thermoelectric system 42. In some embodiments, a single sensor 62 is used; although in other embodiments, the body support 10 can include multiple sensors 62. The sensor(s) 62 can be positioned on or in the body support 10 to enable measurement of the temperature (and therefore the firmness) of the visco-elastic foam of the body support 10. For example, one or more sensors 62 can be located on the top surface 39 of the third layer 22, the bottom surface 41 of the third layer 22 and/or on the top surface 34 of the second layer 18 at any location along the length and width of the body support 10. Alternatively or in addition, one or more sensors 62 can be recessed within or embedded within the top surface 39 of the third layer 22, the bottom surface 41 of the third layer 22 and/or the top surface 34 of the second layer 18 at any location along the length and width of the body support 10. In this manner, the sensor(s) 62 can detect the temperature of the second and/or third layers 18, 22 at such locations, and can provide such temperature information to the controller 66. In these and other embodiments, one or more sensor(s) 62 are positioned outside of the body support 10 and instead detect the temperature of the environment around the body support 10 (thereby indirectly enabling an estimate to be made of the temperature of the second and/or third layers 18, 22 or of any other layer of the body support 10).

[0031] As just described, the sensor(s) 62 in the illustrated embodiment are positioned to sense the temperature of the second layer 18 (or the second and third layers 18, 22), and can provide that information to the controller 66. In some embodiments, one or more additional sensors (not shown) can be used to sense, for example, pressure, movement, moisture, or other parameters to be provided to the controller 66. Temperature or other data can be transmitted from the sensor(s) 62 to the controller 66 via a hardwired connection, or via a wireless connection (in which case the sensor(s) 62 can each be connected to one or more suitable transmitters, and the controller 66 can be connected to a suitable receiver for receiving the sensor data).

[0032] In some embodiments, the controller 66 is embedded into the body support 10, away from the resting position of the user's body upon the body support 10. For example, the controller 66 can be located within a recess in the first layer 14, such as in a side surface of the first layer 14.

[0033] The controller 66 can be a programmable or non-programmable microprocessor capable of receiving temperature data from the sensor(s) 62 of the body support 10, processing the temperature data, and responding by changing operation of the thermoelectric system 42. The controller 66 can be electrically coupled to a user interface (shown embedded within the first layer 14 of the body support 10 in Fig. 2, but alternatively or also being a hand-held unit tethered to body support 10 or in wireless communication with a transceiver connected to the sensor(s) 62 and Peltier devices) having one or more user-manipulatable controls, such as buttons, dials, switches, a touch screen, and the like. These controls can enable a user of the body support 10 to input desired firmness settings and/or commands to change operation of the thermoelectric system 42 (e.g., supply power to, stop the supply of power to, increase power to, and/or decrease power to the Peltier devices 50), and in some embodiments can display body support information to the user (e.g., body support firmness, body support temperature, and the like). In some embodiments, the controls include one or more user-manipulatable controls to change the thermoelectric system 42 from a heating mode to a cooling mode, or from a cooling mode to a heating mode using the Peltier devices 50.

[0034] Accordingly, the controller 66 can receive inputs from a user via a user interface to adjust the firmness of the body support 10 (by changing the temperature of the visco- elastic foam of the body support 10). This adjustment can be made by the controller stopping, starting, increasing, and/or decreasing power supplied to the Peltier devices 50, whether to the same Peltier devices 50 for heating and cooling, or to different sets of Peltier devices for heating and cooling, respectively. [0035] With continued reference to the illustrated embodiment, a user can adjust or tune the temperature of the visco-elastic foam in the body support 10 to a degree that is proportional to a desired mattress firmness. In operation, the sensor(s) 62 sense the temperature of the body support 10 (e.g., the visco-elastic foam layer 14, 18, and/or 22), and provides the sensed temperature to the controller 66. The controller 66 can compare the sensed temperature to a preferred or desired temperature for the body support 10 (e.g., the first, second, and/or third layer 14, 18, 22) input by the user. The controller 66 can thereafter automatically adjust the temperature of the body support 10 by controlling the thermoelectric system 42 as described above until the measured temperature is the same as the desired temperature. For example, if the measured temperature is cooler than the desired temperature, then the controller 66 can increase the amount of heating (thermal) energy delivered by the Peltier devices 50. In some embodiments, the control system 66 controls the amount of electrical energy supplied to the Peltier devices 50 of the thermoelectric system 42 to increase and/or decrease the temperature of the first layer 14.

[0036] In some embodiments, the thermoelectric system 42 is automatically activated (i.e., the supply of power to the Peltier devices 50 is changed) when a user is sensed to have rested upon the body support 10, such as by a pressure sensor as described above. Alternatively, the thermoelectric system 42 can be activated by the user via the user interface described above. In any case, if the temperature sensed by the sensor(s) 62 indicate that the firmness of the body support 10 is too high or too low, the controller 66 can automatically adjust the thermoelectric system 42 accordingly (as also described above) to provide heat to or draw heat away from the body support 10 in order to lower or raise the firmness of the visco-elastic foam, respectively. In some embodiments, the controller 66 can be programmed to activate the thermoelectric system 42 at a particular time of day, thereby readying the body support 10 for the user in advance of use.

[0037] In some embodiments, the controller 66 can determine when the programmed parameter (e.g., layer temperature, corresponding to layer firmness) has been reached based on data received from the sensor(s) 62. Furthermore, the controller 66 can automatically change operation of the thermoelectric system 42 (e.g., turn the thermoelectric system 42 off, reducing power to the Peltier devices 50 of the thermoelectric system, and the like) in response to reaching the programmed, desired and/or preferred parameter. [0038] In some embodiments, the controller 66 can regulate the temperature of one or more visco-elastic foam layers for multiple users (i.e., multiple temperature settings) and/or can regulate the temperature of one or more areas of a visco-elastic foam layer for the same user (e.g., head, torso, and leg areas of the body support 10). For example, the body support 10 can be a mattress having two adjacent areas upon which two users can respectively lie. One of the two areas can be programmed to a particular firmness, while the other area can be programmed to a different firmness. In such embodiments, at least two sets of Peltier devices 50 can be located in different areas of the body support 10, and can be independently controlled by the controller 66 as described above. Any number of different areas of the body support 10 can have dedicated sets of Peltier devices 50 for heating and/or cooling such areas to different temperatures.

[0039] In some embodiments, multiple layers of Peltier devices 50 located in the same or different layers of visco-elastic foam in the body support 10 can be utilized to increase and/or decrease the temperature and resulting firmness of one or more layers of visco-elastic foam at different depths of the body support 10.

[0040] In the illustrated embodiment of Figs. 1-3, the Peltier devices 50 of the body support 10 are located between two layers 14, 18 of the body support 10, and can be recessed within either layer 14, 18 as desired. In other embodiments, the Peltier devices 50 can be partially or entirely embedded within a layer of the body support 10, such as entirely or partially within the visco-elastic second layer 18 of the illustrated body support 10. In such embodiments, the layer (e.g., layer 18) can be molded (e.g., injection molded, spray molded, and the like) as a single layer, with the Peltier devices 50 embedded in the molded layer during manufacture.

[0041] The body support 10 illustrated in Figs. 1-3 is presented in the form of a mattress. However, it will be appreciated that the features of the body support 10 described above are applicable to any other type of body support having any size and shape. By way of example only, any of the features described above are equally applicable to mattress toppers, overlays, futons, sleeper sofas, seat cushions, seat backs, and any other element used to support or cushion any part or all of a human or animal body. Accordingly, as used herein, the term "body support" is intended to refer to any and all of such elements (in addition to mattresses). [0042] Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the invention described. For example, although the use of Peltier devices 50 is described for adjusting the temperature (and therefore the firmness) of the top two layers of foam 18, 22 in the illustrated embodiment, it will be appreciated that such devices can be positioned anywhere within the depth of a body support 10 and can be operated in a manner similar to that described above to adjust the temperature (and therefore the firmness) of any foam layer located at any depth within a body support 10. Control over the firmness of layers deeper within the body support 10, such as visco-elastic layers located deeper within the body support 10, can still provide a degree of control of the overall firmness of the body support 10.

[0043] Various features and advantages of the invention are set forth in the following claims.